Brake Shoe Welding Machine

This special purpose projection Welding Machine is specially designed for welding brake shoe assemblies. The machine is equipped with basic welding Transformer, Microprocessor based control, pneumatically actuated vertical welding head and special rotary indexing fixture with drives etc. The general layout of the machine is as shown in figure enclosed.

Operation:
The web is located on the rotating fixture and the rim is placed correctly locating its relative position with respect to the web. The welding is initiated by foot-switch. The weld schedule is executed and the fixture automatically indexes to the next projection.

In case foot-press continues to be pressed, the weld schedule is repeated. This continues as long as the foot-switch depressed. Each rotary table carries two fixtures. Hence one fixture is free for loading/ unloading when the other is being welded. It is feasible for the operator to keep the machine in continues operation whilst loading/unloading the fixtures(electrodes) sequentially. The ‘OFF TIME’ setting in the weld schedule can be used to control the cycle time without hampering weld quality and to suit operator convenience.

Constuction:
The main frame of machine is of heavy, rigidly reinforced welded steel construction. It combines a compact streamlined appearance with maximum resistance to mechanical deflection. The transformer is housed inside the machine frame. The drive system comprising of the motor, reduction gear box, and clutch brake are mounted on the base of the machine and connected to the rotary indexing table. The fixture assemblies also carry the indexing cams preset for the specific component and hence no setting is required each change of job.

Welding Transformer:
Transformer of a special type, conforming to IS: 4804, Part I 1968, is used. It is water cooled, with core of high grade copper are of ample section. The secondary is of special hollow section for efficient water cooling. Heavy duty class ‘F’ insulation is used. A thermo-switch mounted on the secondary trips the control circuit in case of temperature rise above preset value to protect transformer fro overheating.

Current Conrol by Transformer Taps:
The tap change link incorporated with the transformer provides a choice of 4 secondary voltages nd current values thereby allowing an adjustment of welding current from 50% to 100%. Tap change links are accessed from machine rear door.

Weldor Control:
Microprocessor based welder control, generally as per specification attached, complete with thyristor contactor is provided.

Cooling Systems:

The transformer, electrodes and thyristors are water cooled and discharge to an open drain pot for visual observation of flow.

Electrode Control System:

Vertical electrodes are actuated by a heavy duty adjustable stroke pneumatic cylinder. The cylinder is operated by a solenoid valve by the weld control. Compressed air at 2 kg/sqcm to 7 kg/sqcm acting through the pneumatic cylinder provides the electrodes force. Machine is provided with air filters, regulators with guage, lubricators etc. together with internal air connections.

Adjustment of Weldign Force:

The welding force is adjusted by setting the air pressure with the help of regulator. Forge function is also settable by proper selection of the parameters in the control.

Note:

As efforts are constantly being made to improve both design and methods of manufacture, machine supplied may differ in details from illustrations and specification given.